Dual-responsive smart actuator based on Ti3C2Tx/polymer bilayer structure for bionic applications

Intelligent actuators are emerging smart electronic devices, that sense external stimuli (such as light, heat, electricity, et al.) and convert them into mechanical energy. They have been widely used in biomedicine, micro or biomimetic robots, artificial muscles, switches, and microsensors. MXenes are a series of new two-dimensional materials. Among them, a representative MXene is Ti3C2Tx. Compared with other MXenes, Ti3C2Tx has the advantages of high thermal conductivity, adjustable structure, chemical stability, surface hydrophilicity, and et al. To date, Ti3C2Tx has been extensively researched. Many kinds of research have been achieved in the fields of sewage treatment, flexible sensors, electromagnetic interference shielding, energy storage/conversion, etc. However, the application of Ti3C2Tx in multi-responsive actuators is rarely mentioned. Here, we propose a bilayer actuator fabricated by a simple hot pressing method that can respond to the stimuli of electricity and light. Thanks to the high electrical conductivity, strong light absorption ability, and low thermal expansion coefficient of Ti3C2Tx, the Ti3C2Tx/polymer actuator driven by the dual stimuli of electricity and light can be obtained when combined with polymer film with a large thermal expansion coefficient. When a driven voltage of 6 V is applied to the Ti3C2Tx/polymer actuator, it will bend toward the direction of the Ti3C2Tx layer, with a bending curvature of 0.5 cm-1. The Ti3C2Tx/polymer actuator can also exhibit a large (0.51 cm-2) and reversible bending deformation under near-infrared light (500 mW cm-2) irradiation. In addition, an electric-driven smart gripper and a light-driven bionic worm were designed to demonstrate the actions of moving objects and crawling. These results not only provide new inspiration for using Ti3C2Tx to design high-performance soft actuators but also reveal the potential of Ti3C2Tx -based actuators in smart devices.